Watch balance wheel

ABSTRACT

An electric-powered watch includes a balance wheel assembly which drives time display means. The balance wheel assembly includes a pivoted balance wheel staff, a central member fixed to the staff, and a balance wheel rim consisting only of a bundle of wires which are adhered together and self-supporting. The wires form a coil which cooperates with one or more magnetic fields to impulse the balance wheel assembly.

United States Patent Inventor Heinz .Vleitinger Pforzheim. Germany Appl. No 857.165 Filed Sept. 1 I. 1969 Patented Aug. 10, 1971 Assignee Timex Corporation Waterbury. Conn.

WATCH BALANCE WHEEL 8 Claims, 4 Drawing Figs.

US. Cl 58/28 R, 58/ 107 Int. Cl G04c 3/04 Field of Search 58/23, 28. 107, 28 A [56] References Cited UNITED STATES PATENTS 3,512.35l 5/l970 Shelley et al M 58/23 A 2953.896 9/l960 Van Horn et al. 58/28 3,492,806 2/1970 Walton 58/23 Primary Examiner-Richard B. Wilkinson Assistant Examiner Edith C. Simmons Attorney-Richard A. Joel, Esq.

ABSTRACT: An electric-powered watch includes a balance wheel assembly which drives time display means. The balance wheel assembly includes a pivoted balance wheel staff, a central member fixed to the staff, and a balance wheel rim consisting only of a bundle of wires which are adhered together and self-supporting. The wires form a coil which cooperates with one or more magnetic fields to impulse the balance wheel assembly.

Patented Aug. 10, 1971.

INVENTOR. HEINZ MEITINGER FIG.4

. Z 25m)" I gmr nn Y5 ofwatches may i has few parts, and

larly to the balance wheel assembly of'an electric powered watch.

Various types of electronic watchcshave been suggested.

For example, watches are being produced in which a battery, within the watchcase, is connected to a circuit .using transistors. Thecircuit isconnected to two hairsprings which transmit electrical pulses to a coil carried by-a balance wheel. The coil moves through a number of magnetic fields created by fixed magnets. It has also been suggested that higher timekeeping accuracy could be obtained by using a piczoelcc tric crystaloscillator as the time base of the watch. The crystal oscillator would synchronize a balance wheel type of motor whichwould drive the time display hands. Bothof thesctypes be called moving coil watches, as the coil is carried by the balance wheel. g a I in both of these types of watches, it is desirable that the rotatable index wheel 24. The index wheel 24, by means of a pinion (not shown), rotates a gear 25 which, in turn, is connected to the othcrgears of the gear train of the watch. The gear trainof the watch rotates the previously mentioned hands 6, 7 and 8. i

The term "time display," as used herein, includes rotatable hands as shown in FIG. l, clcctro optical display means such ii and dividing circuit 14 need not be used and may be balance wheel be sturdy,,inexpensive, small in. size, and that it the balance wheel moves through the' magnetic fields. S uch eddy currents are a waste-of power.

It is the objective of the present invention to provide amoving coil balance wheclassembly which is sturdy, low in cost,

which does not create undesirable eddy currents.

it is the further objective of the present invention to provide a moving coil type of balance wheel which is small in size, so

1 that it may fit in a ladicswatch, and yet whichmay be exactly balanced (poised) by convcntionalmethods.

Other objectives of the present invention will be apparent from thefollowing detailed description ofthcinventors best mode of practicing the invention, the description being taken in conjunction. with the accompanying drawings. in the drawings:

FlG.l is a top plan view, partly cut away, of the watch of the present invention;

FIG. 2 is a side plan view of the balance wheel assembly; FIG. 3 is a front plan view of the coil; and- FIG. 4. is a top'plan view of the coil omitted from the watch.

The motor unit of the watch is shown in greater detail in FIG. 2. The coil 20 is wound about andattached to a disc unit consisting of a bottom stabilization disc 31 and a poising disc 36. The top and bottom discs may be a unitary member. The top disc 36 is used for final poising, that is, it is drilled or cut into to attain the final balanced the balance wheel assembly.

The shape of the coil, which preferably is about a sector of a disc with rounded corners, is selected to initially poise the balance wheel. The discs 31 and 36, with their attached coil 20, are fixed to the balance wheel staff 33. The coil passes between axially poled magnets 21a and 21b, of opposite polarity, andan upper shunt 30. The magnets 21a and 2lb are fixed on a lower shunt 22 which is attached to the frame plate. The coil is electrically connected to hairspring l9 and a second hairspring (not shown), although other connecting means may be used. The sccond'hairspring may use the lower disc as its hub.

As shown in. FIG. 4, the coil is wound using a front positioning pin 34 andrear positioning pins 350,151) and 350, which are parts of a removable winding tool. The coil, of fine wire, is wound around the pins 34, 35a, 35b and 350 and also around the disc 31. Preferably the coil is directly wound on the disc.v

in FIG. I the horologieal device of the present invention is I shown as a wristwatch; although it is applicable to other types of horological. instruments. 1

The wristwatch includes a case i having a bezel portion. 2. A

crystal 3 covers a dial 4-having, on its face, numbers 5 or other indicia of time. The time is indicated, as in conventional watches, by a sccondshand-6, a minutes hand '7, and an hours base II by means of line 12. Preferably the time base it is a high frequency piezoelectric oscillator. The high output frequency of the time base it, by means of line 13, is provided to the dividing circuit 14, which counts down its high frequency. The output of the dividing circuit 14, by line i5, is connccted to a drive circuit 16. The output of the drive circuit, by line I7, is connected to thc outer end of hairspring l9. The

inner end of the hairspring is electrically connected to one end of the coil 20. The opposite end of the coil 20 is connected to The coil may be wound using conventional coil-winding machinery. The coil is preferably self-supporting, that is, its

- windings have an adhesive material which joins the windings together. For example, the wire may be coated with a heat-activated resin and the coil, after winding but before the pins are moved, placed in an oven to melt the resin coating on the wires and form the cell into a unitary mass.

After the coil is wound and formed, the coil is lifted from the pins 34, 3511,35!) and 350. It will retain its shape and form.

The balance wheel assembly is then poised. The dispoising caused by the tolerances of the positioning pins may be low,

a second. hairspring (not shown), or other connection means,

which is connected tothe frameplute, the electrical ground.

The battery it) is used, as shown by line 26, to power the dividing circuit and, by line 27, to power the drive circuit. A suitaabout 0.0008 inch, so that the poising may be accomplished by a removal of material from the top poising disc.

I claim:

I. A balance wheel assembly for an electric-powered watch, the assembly including a balance wheel staff, a central poising member adapted to poise fixed to the staff, and a balance wheel rim extending completely around and fixed to the central member, said rim consisting of only a bundle of fine windings and means to adhere the windings together.

2. A balance wheel assembly as in claim 1 wherein the central member consists of a stabilization disc and a poising disc and the coil is fixed in a slot formed between the two discs.

3. A balance wheel assembly as in claim I wherein the shape of the coil, viewed from a top plan view, is approximately a sector of a disc, the sector having rounded corners.

4. An electronic watch comprising a frame plate, a source of electric current, a piezoelectric crystal oscillator connected to said current source, a frequency-dividing circuit connected to said oscillator, a drive circuit coupled to the output of said "means said balance wheel assembly further including a H balance wheel staffpivoted in the frame plate, a central poising member fixed to the balance wheel staff, and abalancewheel rim extending completely'around an'd fixedto the poising member, said consisting only of a bundle of fine windings.

v 5. An electronic watch as in claim 4 wherein the means to create a magnetic field'consists of two axially poled magnets I of opposite polarity.

6. A balance wheel assembly as in claim 4 wherein the central member consists of a stabilizationidisc and a poising disc and the coil is fixed in a slot formed between 'the two discs.

8. A balance wheel assembly as in claim 4 shaped in such manner that except for the wire of the coil no other metallic parts move through'the airgap of the drivingmagnet. 

1. A balance wheel assembly for an electric-powered watch, the assembly including a balance wheel staff, a central poising member adapted to poise fixed to the staff, and a balance wheel rim extending completely around and fixed to the central member, said rim consisting of only a bundle of fine windings and means to adhere the windings together.
 2. A balance wheel assembly as in claim 1 wherein the central member consists of a stabilization disc and a poising disc and the coil is fixed in a slot formed between the two discs.
 3. A balance wheel assembly as in claim 1 wherein the shape of the coil, viewed from a top plan view, is approximately a sector of a disc, the sector having rounded corners.
 4. An electronic watch comprising a frame plate, a source of electric current, a piezoelectric crystal oscillator connected to said current source, a frequency-dividing circuit connected to said oscillator, a drive circuit coupled to the output of said dividing circuit, a time display means, and a balance wheel assembly means for creating a magnetic field cooperating with and connected with said drive circuit to drive said time display means, said balance wheel assembly further including a balance wheel staff pivoted in the frame plate, a central poising member fixed to the balance wheel staff, and a balance wheel rim extending completely around and fixed to the poising member, said consisting only of a bundle of fine windings.
 5. An electronic watch as in claim 4 wherein the means to create a magnetic field consists of two axially poled magnets of opposite polarity.
 6. A balance wheel assembly as in claim 4 wherein the central member consists of a stabilization disc and a poising disc and the coil is fixed in a slot formed between the two discs.
 7. A balance wheel assembly as in claim 4 wherein the shape of the coil, viewed from a top plan view, is approximately a sector of a disc, the sector having rounded corners, the shape being such as to balance the coil about the center staff and to avoid a high inductive EMF at 180* from the zero line.
 8. A balance wheel assembly as in claim 4 shaped in such a manner that except for the wire of the coil no other metallic parts move through the airgap of the driving magnet. 